Current collector for an electromechanical cell

ABSTRACT

A current collector for an electrochemical cell includes a member having an outer member and an inner member coupled to the outer member by a plurality of flexible arms configured to allow the inner member to move relative to the outer member.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.13/571,183, filed. Aug. 9, 2012, which is a continuation of U.S. patentapplication Ser. No. 13/087,277, filed Apr. 14, 2011, which is acontinuation of International Patent Application No. PCT/US2009/065365,filed Nov. 20, 2009, which claims the benefit of and priority to U.S.Provisional Patent Application No. 61/116,993, filed Nov. 21, 2008 andU.S. Provisional Patent Application No. 61/172,148, filed Apr. 23, 2009.The entire disclosures of U.S. patent application Ser. Nos. 13/571,183and 13/087,277, International Patent Application No. PCT/US2009/065365,U.S. Provisional Patent Application No. 61/116,993, and U.S. ProvisionalPatent Application Nos. 61/116,993 and 61/172,148 are incorporatedherein by reference in their entireties for all purposes.

BACKGROUND

The present application relates generally to the field of batteries andbattery systems. More specifically, the present application relates tobatteries and battery systems that may be used in vehicle applicationsto provide at least a portion of the motive power for the vehicle.

Vehicles using electric power for all or a portion of their motive power(e.g., electric vehicles (EVs), hybrid electric vehicles (HEVs), plug-inhybrid electric vehicles (PHEVs), and the like, collectively referred toas “electric vehicles” (xEVs)) may provide a number of advantages ascompared to more traditional gas-powered vehicles using internalcombustion engines. For example, electric vehicles may produce fewerundesirable emission products and may exhibit greater fuel efficiency ascompared to vehicles using internal combustion engines (and, in somecases, such vehicles may eliminate the use of gasoline entirely, as isthe case of certain types of PHEVs).

As electric vehicle technology continues to evolve, there is a need toprovide improved power sources (e.g., battery systems or modules) forsuch vehicles. For example, it is desirable to increase the distancethat such vehicles may travel without the need to recharge thebatteries. It is also desirable to improve the performance of suchbatteries and to reduce the cost associated with the battery systems.

One area of improvement that continues to develop is in the area ofbattery chemistry. Early electric vehicle systems employednickel-metal-hydride (NiMH) batteries as a propulsion source. Over time,different additives and modifications have improved the performance,reliability, and utility of NiMH batteries.

More recently, manufacturers have begun to develop lithium-ion batteriesthat may be used in electric vehicles. There are several advantagesassociated with using lithium-ion batteries for vehicle applications.For example, lithium-ion batteries have a higher charge density andspecific power than NiMH batteries. Stated another way, lithium-ionbatteries may be smaller than NiMH batteries while storing the sameamount of charge, which may allow for weight and space savings in theelectric vehicle (or, alternatively, this feature may allowmanufacturers to provide a greater amount of power for the vehiclewithout increasing the weight of the vehicle or the space taken up bythe battery system).

It is generally known that lithium-ion batteries perform differentlythan NiMH batteries and may present design and engineering challengesthat differ from those presented with NiMH battery technology. Forexample, lithium-ion batteries may be more susceptible to variations inbattery temperature than comparable NiMH batteries, and thus systems maybe used to regulate the temperatures of the lithium-ion batteries duringvehicle operation. The manufacture of lithium-ion batteries alsopresents challenges unique to this battery chemistry, and new methodsand systems are being developed to address such challenges.

It would be desirable to provide an improved battery module and/orsystem for use in electric vehicles that addresses one or morechallenges associated with NiMH and/or lithium-ion battery systems usedin such vehicles. It also would be desirable to provide a battery moduleand/or system that includes any one or more of the advantageous featuresthat will be apparent from a review of the present disclosure.

SUMMARY

One exemplary embodiment relates to a current collector for anelectrochemical cell including a member having an outer member and aninner member coupled to the outer member by a plurality of flexible armsconfigured to allow the inner member to move relative to the outermember.

Another exemplary embodiment relates to flexible current collector foran electrochemical cell. The current collector includes an outerportion, and inner portion, and a plurality of connecting members. Eachof the connecting members has a first end coupled to the outer portionand a second end coupled to the inner portion. The connecting membersare configured to allow the inner portion to move relative to the outerportion.

Another exemplary embodiment relates to an electrochemical cellincluding a current collector including a member having an outer memberand an inner member coupled to the outer member by a plurality offlexible arms configured to allow the inner member to move relative tothe outer member.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a vehicle including a battery moduleaccording to an exemplary embodiment.

FIG. 2 is a cutaway schematic view of a vehicle including a batterymodule according to an exemplary embodiment.

FIG. 3 is a perspective view of an electrochemical cell according to anexemplary embodiment.

FIG. 4 is a partial cross-sectional view of the electrochemical cellshown in FIG. 3 taken along line 4-4 in FIG. 3.

FIG. 5 is a partial cross-sectional view of electrodes and separatorsfor an electrochemical cell according to an exemplary embodiment.

FIG. 6 is a perspective view of a cell element provided in the form of ajelly roll configuration according to an exemplary embodiment.

FIG. 7 is a cross-sectional view of the cell element shown in FIG. 6taken along line 7-7 in FIG. 6.

FIG. 8 is a top view of a current collector coupled to a cell elementaccording to an exemplary embodiment.

FIG. 9 is an exploded perspective view of the current collector and cellelement shown in FIG. 8.

FIG. 9A is a perspective view of the current collector shown in FIG. 9coupled to the cell element shown in FIG. 9 with a tab of the currentcollector having been folded according to an exemplary embodiment.

FIG. 10 is a perspective view of a current collector according toanother exemplary embodiment.

FIG. 11 is a top view of the current collector shown in FIG. 10.

FIG. 12 is a top view of the current collector shown in FIG. 10 showncoupled to a cell element according to an exemplary embodiment.

FIG. 12A is an exploded side view of the current collector and cellelement shown in FIG. 12 according to an exemplary embodiment.

FIG. 12B is an exploded side view of the current collector and cellelement shown in FIG. 12 according to another exemplary embodiment.

FIG. 13A is a partial cross-sectional schematic view of the currentcollector and cell element shown in FIG. 12B with a tab of the currentcollector having been folded according to an exemplary embodiment.

FIG. 13B is a partial cross-sectional schematic view of the currentcollector shown in FIG. 13A coupled to the cell element shown in FIG.13A according to an exemplary embodiment.

FIG. 14 is a top view of a current collector according to anotherexemplary embodiment.

FIG. 15 is a cross-sectional view of the current collector shown in FIG.14 taken along lines 15-15 in FIG. 14.

FIG. 16 is a side view of the current collector shown in FIG. 14.

FIG. 17 is a perspective view of the current collector shown in FIG. 14being coupled to a cell element according to an exemplary embodiment.

FIG. 18A is a partial cross-sectional schematic view of the currentcollector and cell element shown in FIG. 17 taken along line 18-18 inFIG. 17.

FIG. 18B is a partial cross-sectional schematic view of the currentcollector shown in FIG. 18A coupled to the cell element shown in FIG.18A according to an exemplary embodiment.

FIG. 19 is a perspective view of a current collector coupled to a cellelement according to another exemplary embodiment.

FIG. 19A is a top view of the current collector shown in FIG. 19.

FIG. 20 is a perspective view of a current collector coupled to a cellelement according to another exemplary embodiment.

FIG. 20A is a top view of the current collector shown in FIG. 20.

FIG. 21 is a perspective view of a current collector coupled to a cellelement according to another exemplary embodiment.

FIGS. 22-23 are perspective views of current collectors according toother exemplary embodiments.

FIG. 24A is a partial cross-sectional view of a cell having a flexiblecurrent collector according to an exemplary embodiment.

FIG. 24B is a partial cross-sectional view of the cell having a flexiblecurrent collector shown in FIG. 24A after a vent has been deployedaccording to an exemplary embodiment.

FIG. 24C is a perspective view of the flexible current collector shownin FIG. 24B according to an exemplary embodiment.

FIG. 24D is a perspective view of a housing for the electrochemical cellshown in FIG. 24 according to another exemplary embodiment.

FIGS. 25-27 are various perspective views of a current collectoraccording to another exemplary embodiment.

FIG. 28 is a perspective view of the current collector shown in FIGS.25-27 provided in an electrochemical cell according to an exemplaryembodiment.

FIG. 29 is a cross-sectional view of the electrochemical cell shown inFIG. 28 taken along lines 29-29 in FIG. 28.

FIG. 30 is a flow diagram of a method of manufacturing anelectrochemical cell according to an exemplary embodiment.

DETAILED DESCRIPTION

FIG. 1 is a perspective view of a vehicle 10 in the form of anautomobile (e.g., a car) having a battery system 20 for providing all ora portion of the motive power for the vehicle 10. Such a vehicle 10 canbe an electric vehicle (EV), a hybrid electric vehicle (HEV), a plug-inhybrid electric vehicle (PHEV), or other type of vehicle using electricpower for propulsion (collectively referred to as “electric vehicles”).

Although the vehicle 10 is illustrated as a car in FIG. 1, the type ofvehicle may differ according to other exemplary embodiments, all ofwhich are intended to fall within the scope of the present disclosure.For example, the vehicle 10 may be a truck, bus, industrial vehicle,motorcycle, recreational vehicle, boat, or any other type of vehiclethat may benefit from the use of electric power for all or a portion ofits propulsion power.

Although the battery system 20 is illustrated in FIG. 1 as beingpositioned in the trunk or rear of the vehicle, according to otherexemplary embodiments, the location of the battery system 20 may differ.For example, the position of the battery system 20 may be selected basedon the available space within a vehicle, the desired weight balance ofthe vehicle, the location of other components used with the batterysystem 20 (e.g., battery management systems, vents or cooling devices,etc.), and a variety of other considerations.

FIG. 2 illustrates a cutaway schematic view of a vehicle 11 provided inthe form of an HEV according to an exemplary embodiment. A batterysystem 21 is provided toward the rear of the vehicle 11 proximate a fueltank 12 (the battery system 21 may be provided immediately adjacent thefuel tank 12 or may be provided in a separate compartment in the rear ofthe vehicle 11 (e.g., a trunk) or may be provided elsewhere in thevehicle 11). An internal combustion engine 14 is provided for times whenthe vehicle 11 utilizes gasoline power to propel the vehicle 11. Anelectric motor 16, a power split device 17, and a generator 18 are alsoprovided as part of the vehicle drive system.

Such a vehicle 11 may be powered or driven by just the battery system21, by just the engine 14, or by both the battery system 21 and theengine 14. It should be noted that other types of vehicles andconfigurations for the vehicle drive system may be used according toother exemplary embodiments, and that the schematic illustration of FIG.2 should not be considered to limit the scope of the subject matterdescribed in the present application.

According to various exemplary embodiments, the size, shape, andlocation of the battery system 21, the type of vehicle 11, the type ofvehicle technology (e.g., EV, HEV, PHEV, etc.), and the batterychemistry, among other features, may differ from those shown ordescribed.

According to an exemplary embodiment, the battery system 21 includes aplurality of electrochemical batteries or cells. The battery system 21may also include features or components for connecting theelectrochemical cells to each other and/or to other components of thevehicle electrical system, and also for regulating the electrochemicalcells and other features of the battery system 21. For example, thebattery system 21 may include features that are responsible formonitoring and controlling the electrical performance of the batterysystem 21, managing the thermal behavior of the battery system 21,containment and/or routing of effluent (e.g., gases that may be ventedfrom an electrochemical cell through a vent), and other aspects of thebattery system 21.

Referring now to FIG. 3, an isometric view of an electrochemical cell 24is shown according to an exemplary embodiment. A battery system (such asbattery system 20, 21) includes a plurality of such electrochemicalcells 24 (e.g., lithium-ion cells, nickel-metal-hydride cells, lithiumpolymer cells, etc., or other types of electrochemical cells now knownor hereafter developed). According to an exemplary embodiment, theelectrochemical cells 24 are generally cylindrical lithium-ion cellsconfigured to store an electrical charge. According to other exemplaryembodiments, the cells 24 could have other physical configurations(e.g., oval, prismatic, polygonal, etc.). The capacity, size, design,terminal configuration, and other features of the cells 24 may alsodiffer from those shown according to other exemplary embodiments.

FIG. 4 is a partial cross-sectional view of a cell 24 such as that shownin FIG. 3 taken along line 4-4 in FIG. 3. According to an exemplaryembodiment, the cell 24 includes a container or housing 25, a cap orcover 42, a bottom portion (not shown), and a cell element 30. Accordingto an exemplary embodiment, the housing 25 may be constructed from aconductive material such as a metal (e.g., aluminum or an aluminumalloy, copper or a copper alloy, etc.). According to an exemplaryembodiment, the cell element 30 is a wound cell element. According toanother exemplary embodiment, the cell element 30 may be a prismatic oroval cell element.

According to an exemplary embodiment, the cell element 30 includes atleast one cathode or positive electrode 36, at least one anode ornegative electrode 38, and one or more separators 32, 34. The separators32, 34 are provided intermediate or between the positive and negativeelectrodes 36, 38 to electrically isolate the electrodes 36, 38 fromeach other. According to an exemplary embodiment, the cell 24 includesan electrolyte (not shown). According to an exemplary embodiment, theelectrolyte is provided in the housing 25 of the cell 24 through a fillhole 41. After completion of filling the cell 24 with electrolyte, afill plug (e.g., such as fill plug 43 as shown in FIGS. 28 and 29) maybe provided in the fill hole 41 to seal the electrolyte inside the cell24.

The cell 24 also includes a negative current collector 40 and a positivecurrent collector (not shown). The negative current collector 40 and thepositive current collector are conductive members that are used tocouple the electrodes 36, 38 of the cell element 30 to the terminals 26,28 of the cell 24. For example, the negative current collector 40couples the negative electrode 38 to the negative terminal 28 (via a tab44) and the positive current collector couples the positive electrode 36to the positive terminal 26 of the cell 24 (e.g., via the housing 25).According to the exemplary embodiment shown in FIG. 4, the tab 44 of thenegative current collector 40 has been at least partially folded or bentback over itself at least one time before being coupled to the negativeterminal 28. According to an exemplary embodiment, the currentcollectors are coupled to the electrodes with a welding operation (e.g.,a laser welding operation).

According to an exemplary embodiment, the cell element 30 has a woundconfiguration in which the electrodes 36, 38 and separators 32, 34 arewound around a member or element provided in the form of a tube ormandrel 50. Such a configuration may be referred to alternatively as ajelly roll configuration. Although the mandrel 50 is shown as beingprovided as having a generally cylindrical shape, according to otherexemplary embodiments, the mandrel 50 may have a different configuration(e.g., it may have an oval or rectangular cross-sectional shape, etc.).It is noted that the cell element 30, although shown as having agenerally cylindrical shape, may also have a different configuration(e.g., it may have an oval, prismatic, rectangular, or other desiredcross-sectional shape).

According to another exemplary embodiment, the electrochemical cell 24may be a prismatic cell having prismatic or stacked cell elements (notshown). In such an embodiment, the positive and negative electrodes 36,38 are provided as plates that are stacked upon one another in analternating fashion, with the separators 32, 34 provided intermediate orbetween the positive and negative electrodes 36, 38 to electricallyisolate the electrodes 36, 38 from each other.

According to an exemplary embodiment, the positive electrode 36 isoffset from the negative electrode 38 in the axial direction as shown inthe partial cross-sectional view shown in FIG. 5. Accordingly, at afirst end of the cell element 30, the wound positive electrode 36 willextend further than the negative electrode 38, and at a second(opposite) end of the cell element 30, the negative electrode 38 willextend further than the positive electrode 36.

One advantageous feature of such a configuration is that currentcollectors may be connected to a specific electrode at one end of thecell 24 without contacting the opposite polarity electrode. For example,according to an exemplary embodiment, a negative current collector 40(e.g., as shown in FIG. 4) may be connected to the exposed negativeelectrode 38 at one end of the cell element 30 and a positive currentcollector (not shown) may be connected to the exposed positive electrode36 at the opposite end of the cell element 30.

According to an exemplary embodiment, the negative current collector 40electrically connects the negative electrode 38 to the negative terminal28 of the cell 24. The negative terminal 28 is insulated from the cover42 of the housing 25 by an insulator 45, as shown in FIG. 4. Accordingto an exemplary embodiment, the positive current collector (not shown)electrically connects the positive electrode 36 to a bottom of thehousing 25. The housing 25 is electrically connected to the cover 42(e.g., as shown in FIG. 4), which in turn is electrically connected tothe positive terminal 26.

FIGS. 6-7 illustrate an exemplary embodiment of a wound cell element 30(e.g., a jelly roll) in which electrodes 36, 38 and separators 32, 34(not shown) are wound around a member or element provided in the form ofa mandrel 50 (e.g., a body, center member, shaft, rod, tube etc.).According to an exemplary embodiment, an adhesive or tape 48 (e.g., asshown in FIG. 6) may be used to position an electrically-insulating wrapor film 46 (e.g., as shown in FIGS. 4 and 6) around the cell element 30in order to at least partially electrically insulate the cell element 30from the housing 25. According to an exemplary embodiment, the film 46is a polymide material such as is commercially available under the tradename Kapton® from E. I. du Pont de Nemours and Company.

According to an exemplary embodiment, the mandrel 50 is provided in theform of an elongated hollow tube 52 and is configured to allow gasesfrom inside the electrochemical cell to flow from one end of theelectrochemical cell (e.g., the top) to the other end of theelectrochemical cell (e.g., the bottom). According to another exemplaryembodiment, the mandrel 50 may be provided as a solid tube.

The mandrel 50 is illustrated, for example, in FIG. 7 as being providedwithin the center of the cell element 30. According to an exemplaryembodiment, the mandrel 50 does not extend all the way to the very topand bottom of the cell element 30. According to other exemplaryembodiments, the mandrel 50 may extend all the way to the top and/orbottom of the cell element 30.

Still referring to FIGS. 6-7, according to an exemplary embodiment, themandrel 50 includes at least one (i.e., one or more) element or drivemember 60 joined to an end of the hollow tube 52. According to anexemplary embodiment, the drive members 60 are configured toelectrically insulate the hollow tube 52 from the electrodes 36, 38.According to another exemplary embodiment, the hollow tube 52 may beprovided in electrical contact with one of the electrodes while beingelectrically insulated from the other electrode. For example, accordingto an exemplary embodiment, the hollow tube 52 may be electricallycoupled to the positive electrode 36 (or negative electrode 38), whilethe hollow tube 52 is electrically isolated from the negative electrode38 (or positive electrode 36) by the drive member 60.

According to an exemplary embodiment, the drive members 60 are formedfrom an electrically-insulating material such as a polymeric material orother suitable material (e.g., a plastic resin) and the hollow tube 52is formed from an electrically (and thermally) conductive material suchas a metallic material or other suitable material (e.g., aluminum oraluminum alloy). According to another exemplary embodiment, the drivemembers 60 are formed from an electrically (and thermally) conductivematerial such as a metallic material or other suitable material (e.g.,aluminum or aluminum alloy) and the hollow tube 52 is formed from anelectrically-insulating material such as a polymeric material or othersuitable material (e.g., a plastic resin). According to anotherexemplary embodiment, both the drive members 60 and the hollow tube 52are formed from an electrically-insulating material such as a polymericmaterial or other suitable material (e.g., a plastic resin).

One advantageous feature of the mandrels 50 as described above is thatthe drive members 60 coupled to the hollow tube 52 keep the positive andnegative electrodes 36, 38 electrically separated from each other.Additionally, when the hollow tube 52 of the mandrel 50 is formed from arelatively low cost material (e.g., a drawn aluminum tube or extrudedaluminum tube), the mandrel 50 may have a lower cost as compared toother mandrels in which the entire assembly is made of a polymericmaterial.

According to other exemplary embodiments, other configurations of thecell element 30 may be used that do not include the mandrel 50 or thedrive members 60 (e.g., a prismatic cell element). Additionally, whilethe cell 24 in FIGS. 4 and 6 is shown according to an exemplaryembodiment as having the exposed negative electrode 38 proximate to thetop of the cell 24 and the exposed positive electrode 36 proximate tothe bottom of the cell 24, according to other exemplary embodiments, theorientation of the cell element 30 (and thus the positions of thecurrent collectors) may be reversed. Additionally, according to otherexemplary embodiments, the terminals 26, 28 of the cell 24 may beprovided on opposite ends of the cell 24 (e.g., a negative terminal 28may be provided on the top of the cell 24 and a positive terminal 26 maybe provided on the bottom of the cell 24).

Referring now to FIGS. 8-9A, a member or element provided in the form ofa current collector or collector plate 140 is shown according to anexemplary embodiment. According to an exemplary embodiment, the currentcollector 140 is provided in the form of a generally flat member with aplurality of legs or extensions 142 and an extension or tab 144 (formed,e.g., by a stamping operation, a laser cutting operation, etc.).According to an exemplary embodiment, the current collector 140 may beformed from a material having a thickness of between approximately 1 and2 millimeters, but may have a greater or lesser thickness accordingother exemplary embodiments. According to various exemplary embodiments,the current collector 140 may be formed from any of a wide variety ofconductive materials such as aluminum or an aluminum alloy (e.g., for apositive current collector), copper or a copper alloy (e.g., for anegative current collector), nickel-plated copper or an alloy thereof,etc.

As shown, the legs 142 are configured to extend across one end of thecell element 30 to contact the edge of the exposed electrode (e.g., thenegative electrode 38). According to another exemplary embodiment, thelegs 142 may extend only partially across the end of the cell element30. While three legs 142 are shown in the exemplary embodiment of FIGS.8-9A, according to other exemplary embodiments, the current collector140 may have a greater or lesser number of legs 142.

As shown in FIG. 9A, according to an exemplary embodiment, the extensionor tab 144 is configured to be folded away from the cell element 30 andat least partially back over the main body 141 of the current collector140. The tab 144 is configured to be coupled to the housing of the cellor to a terminal of the cell to create a conductive path between theelectrode and the housing or terminal (e.g., similar to that shown inFIG. 4). According to another exemplary embodiment, the tab 144 may befolded or bent at least partially over itself multiple times (e.g.,similar to that shown in FIG. 4). The tab 144 provides a substantiallyflexible connection between the electrode of the cell element 30 and theterminal or housing and allows the cell element 30 to move relative tothe terminal or housing if required.

As best seen in FIG. 8, the ends of the legs 142 may include a roundedor curved shape to complement the perimeter of the cell element 30.According to other exemplary embodiments, the legs 142 (including theends of the legs) may have other shapes and/or sizes. According to anexemplary embodiment, the legs 142 of the current collector areseparated from one another by an Angle A of approximately 120 degrees.According to other exemplary embodiments, the legs 142 may be separatedfrom one another by a greater or smaller angle.

According to an exemplary embodiment, the current collector 140 may becoupled to the electrode with a welding operation (e.g., a laser weldingoperation) along the legs 142 of the current collector 140 (e.g., suchas along weld lines 146 as shown in FIG. 8). As such, the welding occursradially with respect to the end of the cell element 30. This allows formore efficient current flow from the electrode of the cell element 30 tothe current collector 140, because the edge of the wound electrode iscoupled (e.g., welded) to the current collector 140 (via the legs 142)multiple times. Additionally, radial welds on a wound cell element (suchas shown in FIG. 9) allow the weld to occur substantially perpendicularto the edge of the electrode, providing for better weld control andrepeatability of the weld from one cell to the next. According to anexemplary embodiment, the welding of the current collector 140 to theelectrode is done prior to the folding of the tab 144, but may occur ata different time according to other exemplary embodiments.

Referring now to FIGS. 10-12B, a current collector 240 is shownaccording to another exemplary embodiment. The current collector 240 issimilar to the current collector 140 of FIGS. 8-9, except the currentcollector 240 of FIGS. 10-12B is formed as a relatively narrow elongatedstrip of material (to allow for the efficient use of material).According to an exemplary embodiment, the current collector 240 may beformed from a material having a thickness of between approximately 1 and2 millimeters, but may have a greater or lesser thickness accordingother exemplary embodiments. According to various exemplary embodiments,the current collector 240 may be formed from any of a wide variety ofconductive materials such as aluminum or an aluminum alloy (e.g., for apositive current collector), copper or a copper alloy (e.g., for anegative current collector), nickel-plated copper or an alloy thereof,etc.

The legs 242 are formed (e.g., by a stamping operation, a laser cuttingoperation, etc.) by a series of generally parallel cuts at one end ofthe strip of material in a longitudinal direction. To form the currentcollector 240, according to an exemplary embodiment, the outer legs 242are folded or otherwise manipulated outward at an angle (see FIG. 12) ofapproximately 120 degrees from one another. According to other exemplaryembodiments, the outer legs may be folded at an angle that is greater orsmaller than 120 degrees.

According to an exemplary embodiment, the legs 242 of the currentcollector 240 are configured to extend across the end of the electrodeof the cell element 30 to contact the edge of the exposed electrode(e.g., the negative electrode or the positive electrode). According toanother exemplary embodiment, the legs 242 may extend only partiallyacross the end of the wound electrode. While three legs 242 are shown inthe exemplary embodiment of FIGS. 10-12, according to other exemplaryembodiments, the current collector 240 may have a greater or lessernumber of legs.

As shown in FIG. 12A, according to one exemplary embodiment, the outerlegs 242 may be bent or folded under the main body 241 of the currentcollector 240 such that the outer legs 242 are substantially parallel tothe inner leg 242. As shown in FIG. 12B, according to another exemplaryembodiment, the outer legs 242 may be bent or folded under the main body241 of the current collector 240 such that the outer legs 242 are at anangle with respect to the plane of the main body 241 (e.g., such asAngle B as shown in FIG. 13A). Additionally, as shown in FIG. 12B, theinner leg 242 may be bent or folded towards the cell element 30 suchthat the inner leg 242 is at an angle with respect to the plane of themain body 241 (e.g., such as Angle B as shown in FIG. 13A). According toan exemplary embodiment, the inner leg 242 may be bent or folded before,after, or consecutively with the bending or folding of the outer legs242.

The current collector 240 may be coupled to the electrode with a weldingoperation (e.g., a laser welding operation) along the legs 242 of thecurrent collector 240 (e.g., such as along weld lines 246 as shown inFIG. 12). As such, the welding occurs radially with respect to the edgeof the electrode of the cell element 30. Similarly to as stated above,radial welding allows for more efficient current flow from the electrodeof the cell element 30 to the current collector 240, and for better weldcontrol and repeatability of the weld from one cell to the next.According to an exemplary embodiment, the welding of the currentcollector 240 to the electrode is done prior to the folding of the tab244, but may occur at a different time according to other exemplaryembodiments.

The current collector 240 also includes an extension or tab 244 that isconfigured to be folded away from the cell element 30 and/or at leastpartially back over the main body 241 of the current collector 240(e.g., such as shown in FIGS. 13A and 13B). The tab 244 is configured tobe coupled to the housing of the cell or to a terminal of the cell tocreate a conductive path between the electrode and the housing orterminal (e.g., similar to that as shown in FIG. 4). According toanother exemplary embodiment, the tab 244 may be folded or bent at leastpartially over itself multiple times (e.g., similar to that as shown inFIG. 4). The tab 244 provides a substantially flexible connectionbetween the electrode and the terminal or housing and allows the cellelement 30 to move relative to the terminal or housing.

Referring to FIGS. 13A and 13B, the inner leg 242 of the currentcollector 240 may be at an angle with respect to the plane of the tab244, shown as Angle B (for clarity, the outer legs 242 are not shown).It is noted that the legs 142 of the current collector 140 (e.g., asshown in FIGS. 8-9A) may also be at an angle with respect to the planeof the tab (e.g., such as shown in FIGS. 13A and 13B). For clarity, onlythe current collector 240 is discussed below, although one of ordinaryskill in the art would know that the embodiment discussed below may alsoapply to the embodiment shown in FIGS. 8-9A or other embodiments notdiscussed.

Referring to FIGS. 13A and 13B, Angle B is chosen so that the legs 242of the current collector 240 bend or crush the edge or side of theelectrode (e.g., the negative electrode 38) as the legs 242 make contactwith the edge of the electrode as the legs 242 are brought down tocontact the edge of the electrode (see, e.g., FIG. 13B). Because theelectrodes of the cell element 30 are wound, each of the electrodes willhave multiple portions extending from the edge of each electrode. Thelegs 242 of the current collector 240 may then be coupled to themultiple portions of the edge of the electrode by a welding operation(e.g., a laser welding operation).

The multiple portions of the edge of the electrode are bent or crushedso that they contact one another to create a substantially continuoussurface. The substantially continuous surface allows for better controlof the penetration of the weld. By controlling the penetration of theweld, a stronger, higher quality, and more repeatable weld may be formedthan is possible with an electrode that hasn't been deformed (e.g., anelectrode that hasn't had the multiple portions of the edge of theelectrode bent to touch one another). The tab 244 of the currentcollector 240 is then coupled to the housing of the cell or to theterminal of the cell to create a conductive path between the electrodeand the housing or terminal.

To create a high quality and repeatable weld between the currentcollector 240 and the electrode, it is desirable for the legs 242 of thecurrent collector 240 to contact as many of the multiple portions of theedge of the electrode as possible. According to an exemplary embodiment,Angle B is between approximately 0 degrees and 30 degrees, but may havean angle that is greater or smaller according to other exemplaryembodiments. According to a particular exemplary embodiment, Angle B isbetween approximately 15 and 25 degrees. According to another particularexemplary embodiment, Angle B is approximately 20 degrees.

Referring now to FIGS. 14-17, a member or element provided in the formof a current collector or collector plate 340 is shown according toanother exemplary embodiment. According to one exemplary embodiment, thecurrent collector 340 is provided as a disc-like member that includesone or more projections, ridges, or protrusions 342 that extend alongone side of the current collector 340. The protrusions 342 of thecurrent collector 340 have corresponding grooves, valleys, troughs,depressions, etc. on the opposite side of the current collector 340.According to other exemplary embodiments, the protrusions 342 may nothave corresponding grooves, valleys, troughs, depressions, etc. on theopposite side of the current collector 340. According to one exemplaryembodiment, the protrusions 342 are configured to crush or compress themultiple portions of the edge of the exposed electrode (e.g., thepositive electrode 36) at an end of the cell element 30 so that themultiple portions contact one another (e.g., as shown in FIG. 18B).

The current collector 340 may be formed (e.g., extruded, stamped, etc.)such that one or more protrusions 342, shown as generally V-shapedridges, extend from a surface of the current collector 340. According toan exemplary embodiment, a tip or edge of the protrusions 342 may have apointed profile. According to another exemplary embodiment, the tip oredge of the protrusions 342 may have a rounded profile. According toother exemplary embodiments, the protrusions 342 may extend all the wayacross the current collector 340 (e.g., as shown in FIG. 14) or mayextend only partially across the current collector 340.

According to another exemplary embodiment, the current collector 340 maysubstantially match the size and shape of the end of the cell element30. According to other exemplary embodiments, the current collector 340may be provided in other shapes and/or sizes (e.g., the currentcollector 340 may cover only a portion of the end of the cell element30). According to an exemplary embodiment, the current collector 340 maybe formed from a material having a thickness of between approximately 1and 2 millimeters, but may have a greater or lesser thickness accordingother exemplary embodiments. According to various exemplary embodiments,the current collector 340 may be formed from any of a wide variety ofconductive materials such as aluminum or an aluminum alloy (e.g., for apositive current collector), copper or a copper alloy (e.g., for anegative current collector), nickel-plated copper or an alloy thereof,etc.

The current collector 340 is coupled to the exposed edge of an electrode(e.g., the positive electrode 36) of the cell element 30 with a weldingoperation (e.g., a laser welding operation). According to an exemplaryembodiment, the current collector 340 is welded to the electrode alongthe protrusions 342 of the current collector 340 (e.g., such as alongweld lines 346 as shown in FIG. 14).

Referring to FIGS. 18A-18B, the protrusions 342 of the current collector340 are configured to crush, bend, or otherwise deform the multipleportions of the exposed edge of the positive electrode 36 when thecurrent collector 340 is coupled to the cell element 30. The protrusions342 cause the multiple portions of the edge of the electrode to contacteach other to create a substantially continuous surface. Thesubstantially continuous surface allows for better control of thepenetration of the weld. By controlling the penetration of the weld, astronger, higher quality, and more repeatable weld may be formed than ispossible with an electrode that has not been deformed.

A surface 344 of the current collector 340 is then coupled to thehousing of the cell or to the terminal to create a conductive pathbetween the electrode and the housing or terminal According to anexemplary embodiment, the surface 344 may include a hole or aperture 348(e.g., as shown in FIG. 17) that is generally aligned with the center ofthe cell element 30.

Referring now to FIGS. 19 and 19A, a member or element provided in theform of a current collector or collector plate 440 is shown according toanother exemplary embodiment. The current collector 440 may be formed bya stamping operation (e.g., from a sheet metal material). According toan exemplary embodiment, the current collector 440 may be formed from amaterial having a thickness of between approximately 1 and 2millimeters, but may have a greater or lesser thickness according otherexemplary embodiments. According to various exemplary embodiments, thecurrent collector 440 may be formed from any of a wide variety ofconductive materials such as aluminum or an aluminum alloy (e.g., for apositive current collector), copper or a copper alloy (e.g., for anegative current collector), nickel-plated copper or an alloy thereof,etc.

According to an exemplary embodiment, the current collector 440 includesone or more lower portions 442 that are configured to be coupled to anelectrode (e.g., the positive electrode 36). The current collector 440also includes one or more upper portions 444 that are configured to becoupled to the housing of the cell or to the terminal of the cell tocreate a conductive path between the electrode and the housing orterminal According to the exemplary embodiment shown in FIG. 19, thecurrent collector 440 includes four lower portions 442 and four upperportions 444. According to other exemplary embodiments, the currentcollector 440 may have greater or fewer upper and/or lower portions.

According to an exemplary embodiment, each of the lower portions 442 areconnected to the upper portion by a member shown as a sidewall orshoulder 450. As shown in FIG. 19, the shoulders 450 may have agenerally rounded profile and may smoothly transition from the lowerportion 442 to the upper portion 444. According to another exemplaryembodiment, each of the lower portions 442 includes at least oneprojection or protrusion 452.

According to an exemplary embodiment, the current collector 440 iscoupled to exposed portions of the edge of the positive electrode 36 bya welding operation (e.g., a laser welding operation) along the lowerportions 442 of the current collector 440 (e.g., such as along weldlines 446 as shown in FIG. 19A). According to one exemplary embodiment,the lower portions 442 may contact, bend, or deform the exposed portionsof the edge of the electrode 36 prior to welding (e.g., similar to thatas shown in FIG. 18B). According to another exemplary embodiment, theexposed portions of the edge of the electrode 36 may be deformed priorto coupling the current collector 440 to the electrode 36. The currentcollector 440 may then be coupled to the cell housing or a terminal withanother welding operation along the upper portions 444 of the currentcollector 440.

Referring now to FIGS. 20 and 20A, a member or element provided in theform of a current collector or collector plate 540 is shown according toanother exemplary embodiment. The current collector 540 may be formed bya stamping operation (e.g., from a sheet metal material). According toan exemplary embodiment, the current collector 540 may be formed from amaterial having a thickness of between approximately 1 and 2millimeters, but may have a greater or lesser thickness according otherexemplary embodiments. According to various exemplary embodiments, thecurrent collector 540 may be formed from any of a wide variety ofconductive materials such as aluminum or an aluminum alloy (e.g., for apositive current collector), copper or a copper alloy (e.g., for anegative current collector), nickel-plated copper or an alloy thereof,etc.

According to an exemplary embodiment, the current collector 540 includesone or more lower portions 542 that are configured to be coupled to anelectrode (e.g., the positive electrode 36). The current collector 540also includes one or more upper portions 544 that are configured to becoupled to the housing of the cell or to the terminal of the cell tocreate a conductive path between the electrode and the housing orterminal According to the exemplary embodiment shown in FIG. 20, thecurrent collector 540 includes four lower portions 542 and four upperportions 544. According to other exemplary embodiments, the currentcollector 540 may have greater or fewer upper and/or lower portions.According to an exemplary embodiment, an opening or aperture 548 isincluded in the current collector 540. The aperture 548 has a centralaxis that is generally aligned with the central axis of the cell element30.

According to an exemplary embodiment, each of the lower portions 542 areconnected to the upper portion by a member shown as a sidewall orshoulder 550. As shown in FIG. 20, the shoulders 550 may have agenerally rounded profile and may smoothly transition from the lowerportion 542 to the upper portion 544. According to another exemplaryembodiment, each of the lower portions 542 extends to the perimeter ofthe cell element 30, while the upper portions 544 extend only partiallyacross the cell element 30. According to various exemplary embodiments,the lower portions 542 and/or upper portions 544 may have otherconfigurations (e.g., the lower portions 542 may extend only partiallyacross the end of the cell element, the upper portions 544 may extendall the way across the end of the cell element, etc.)

According to an exemplary embodiment, the current collector 540 iscoupled to exposed portions of the edge of the positive electrode 36 bya welding operation (e.g., a laser welding operation) along the lowerportions 542 of the current collector 540 (e.g., such as along weldlines 546 as shown in FIG. 20A). According to one exemplary embodiment,the lower portions 542 may contact, bend, or deform the exposed portionsof the edge of the electrode 36 prior to welding (e.g., similar to thatas shown in FIG. 18B). According to another exemplary embodiment, theexposed portions of the edge of the electrode 36 may be deformed priorto coupling the current collector 540 to the electrode 36. The currentcollector 540 may then be coupled to the cell housing or a terminal withanother welding operation along the upper portions 544 of the currentcollector 540.

Referring now to FIG. 21, a member or element provided in the form of acurrent collector or collector plate 640 is shown according to anexemplary embodiment. The current collector 640 may be formed from astamping process, a laser cutting process, or other suitable process.According to an exemplary embodiment, the current collector 640 may beformed from a material having a thickness of between approximately 1 and2 millimeters, but may have a greater or lesser thickness accordingother exemplary embodiments. According to various exemplary embodiments,the current collector 640 may be formed from any of a wide variety ofconductive materials such as aluminum or an aluminum alloy (e.g., for apositive current collector), copper or a copper alloy (e.g., for anegative current collector), nickel-plated copper or an alloy thereof,etc.

As shown in FIG. 21, the current collector 640 includes a first or outermember 648 that is connected to a second or inner member 644 by aplurality of members or arms 642. As shown in FIG. 21, the outer member648 is connected to the inner member 644 by four arms 642. According toother exemplary embodiments, the outer member 648 may be connected tothe inner member 644 by a greater or lesser number of arms having thesame or different configuration as shown in FIG. 21.

According to the exemplary embodiment shown in FIG. 21, the outer member648 is provided in the form of a ring or ring-like structure. In theembodiment shown, a perimeter of the outer member 648 substantiallymatches/aligns with the perimeter of the cell element 30. Also accordingto the exemplary embodiment shown in FIG. 21, the inner member 644 has agenerally circular shape.

According to the exemplary embodiment shown in FIG. 21, each of theplurality of arms 642 includes a first portion connected to the outermember 648 and a second portion connected to a member or extension 650.The extension 650 connects the arm 642 to the inner member 644. As shownin FIG. 21, the first portion of each of the arms 642 extends out fromthe outer member 648 in a generally perpendicular direction (i.e., thefirst portion extends generally perpendicular out from the outer member648). According to an exemplary embodiment, the extension 650 extendsout from each of the arms 642 at a point between first and second endsof the arms 642 (e.g., at an approximate midpoint between the first andsecond ends of the arms 642). According to an exemplary embodiment, theinner member 644 can move relative to the outer member 648 because ofthe flexibility of the arms 642 and/or the extensions 650.

According to an exemplary embodiment, the arms 642 and/or the outermember 648 are coupled (e.g., by laser welding) to and edge of anelectrode of the cell element 30 (e.g., such as along weld lines 646 asshown in FIGS. 21 and 24C) and the inner member 644 is coupled (e.g., bylaser welding) to a portion of the housing of the cell or a terminal ofthe cell (e.g., such as along weld lines 658 as shown in FIG. 24C). Asshown in FIG. 24C, the weld lines 646 of the arms 642 and the weld lines658 of the inner member 644 do not align when the vent 70 is deployed.In particular, the lines 642 and 658 are non-parallel (e.g., skewed) asa result of circumferential movement (e.g., twisting) of the arms 642about an axis 638 of the current collector 640. In other words, when thevent 70 deploys, the arms 642 move in an axial direction along the axis638 as well as in a circumferential direction about the axis 638.According to an exemplary embodiment, the welding of the arms 642 isperformed radially across the edge of the electrode of the cell element30 (e.g., as shown in FIG. 21). According to another exemplaryembodiment, the inner member 644 is coupled to the edge of the electrodeof the cell element 30 and the arms 642 and/or the outer member 648 arecoupled to the housing or the terminal.

According to an exemplary embodiment, the geometry of the outer member648, arms 642, extensions 650, and inner member 644 define a pluralityof apertures or slots. These apertures or slots allow the currentcollector 640 to substantially flex (e.g., move, bend, deflect, etc.) ifrequired (e.g., when a vent deploys from the bottom of the housing). Forexample, as shown in FIG. 24B, the inner member 644 is configured toflex with respect to the outer member 648 when the vent 70 deploys fromthe end of the cell 24.

Having a flexible current collector allows for increased length of thecell element inside the housing (e.g., to maximize the power capacity ofthe cell). The flexible current collector also allows the cell elementto remain substantially fixed during deployment of a vent. The flexiblecurrent collector also helps to isolate the vent from shock andvibration during handling and assembly and during use of the cell.

Referring now to FIG. 22, a current collector 740 is shown according toanother exemplary embodiment. The current collector 740 is provided withsimilar but slightly different geometry than that of the currentcollector 640 shown in FIG. 21. The current collector 740 may be formedfrom a stamping process, a laser cutting process, or other suitableprocess. According to an exemplary embodiment, the current collector 740may be formed from a material having a thickness of betweenapproximately 1 and 2 millimeters, but may have a greater or lesserthickness according other exemplary embodiments. According to variousexemplary embodiments, the current collector 740 may be formed from anyof a wide variety of conductive materials such as aluminum or analuminum alloy (e.g., for a positive current collector), copper or acopper alloy (e.g., for a negative current collector), nickel-platedcopper or an alloy thereof, etc.

As shown in FIG. 22, the current collector 740 includes a first or outermember 748 that is connected to a second or inner member 744 by aplurality of members or arms 742. As shown in FIG. 22, the outer member748 is connected to the inner member 744 by four arms 742. According toother exemplary embodiments, the outer member 748 may be connected tothe inner member 744 by a greater or lesser number of arms.

According to the exemplary embodiment shown in FIG. 22, the outer member748 is provided in the form of a ring or ring-like structure. Accordingto an exemplary embodiment, a perimeter of the outer member 748substantially matches/aligns with a perimeter of the cell element.According to the exemplary embodiment shown in FIG. 22, the inner member744 has a generally circular shape.

According to the exemplary embodiment shown in FIG. 22, each of theplurality of arms 742 includes a first portion connected to the outermember 748 and a second portion connected to a member or extension 750.The extension 750 connects the arm 742 to the inner member 744. As shownin FIG. 22, the first portion of each of the arms 742 extends out fromthe outer member 748 in a generally perpendicular direction (i.e., thefirst portion extends generally perpendicular out from the outer member748). According to an exemplary embodiment, the extension 750 extendsout from each of the arms 742 at a point between first and second endsof the arms 742 (e.g., at a point near the first end of the arms 742).According to an exemplary embodiment, the inner member 744 can moverelative to the outer member 748 because of the flexibility of the arms742 and/or the extensions 750.

According to an exemplary embodiment, the arms 742 and/or the outermember 748 are coupled (e.g., by laser welding) to an edge of anelectrode of the cell element and the inner member 744 is coupled (e.g.,by laser welding) to a portion of the housing of the cell or a terminalof the cell. According to an exemplary embodiment, the welding of thearms 742 is performed radially across the end of the cell element.According to another exemplary embodiment, the inner member 744 iscoupled to the edge of the electrode of the cell element and the arms742 and/or the outer member 748 are coupled to the housing or theterminal.

According to an exemplary embodiment, the geometry of the outer member748, arms 742, extensions 750, and inner member 744 define a pluralityof apertures or slots. These apertures or slots allow the currentcollector 740 to substantially flex (e.g., move, bend, deflect, etc.) ifrequired (e.g., when a vent deploys from the bottom of the housing). Forexample, the inner member 744 is configured to flex with respect to theouter member 748 (or vice-versa). It should be noted that the arms 742are rotationally symmetric. For example, rotation of the currentcollector 742 approximately 90 degrees about the axis 638 results in asubstantially identical orientation.

Referring now to FIG. 23, a current collector 840 is shown according toanother exemplary embodiment. The current collector 840 may be formedfrom a stamping process, a laser cutting process, or other suitableprocess. According to an exemplary embodiment, the current collector 840may be formed from a material having a thickness of betweenapproximately 1 and 2 millimeters, but may have a greater or lesserthickness according other exemplary embodiments. According to variousexemplary embodiments, the current collector 840 may be formed from anyof a wide variety of conductive materials such as aluminum or analuminum alloy (e.g., for a positive current collector), copper or acopper alloy (e.g., for a negative current collector), nickel-platedcopper or an alloy thereof, etc.

As shown in FIG. 23, the current collector 840 includes a first or outermember 848 that is connected to a second or inner member 844. As shownin FIG. 23, there are two outer members 848 that are connected to theinner member 844. According to other exemplary embodiments, there may bea greater or lesser number of outer members 848. According to anexemplary embodiment, each of the outer members 848 are connected to amember or element shown as an arm 842 that in turn is connected to theinner member 844. According to the exemplary embodiment shown in FIG.23, the outer member 848 is provided in the form of an enlarged portionof outer arm 842. The arm 842 has a spiral shape about the inner member844. That is, the arm 842 emanates from the inner member 844 and has anarcuate shape from the inner member 844 to the outer member 848. Asshown, the arm 842 increases in width from the inner member to the outermember 848.

As shown in FIG. 23, each of the arms 842 includes an outer portion 850and an inner portion 852. According to an exemplary embodiment, an outerportion 850 of the arm 842 substantially matches/aligns with a perimeterof the cell element. As shown in FIG. 23, each of the inner portions 852of the arms 842 double back along at least a portion of the outerportion 850 of the arms 842 before connecting to the inner member 844.

According to an exemplary embodiment, the outer portion 850 of the arms842 and/or the outer members 848 are coupled (e.g., by laser welding) toan edge of an electrode of the cell element and the inner member 844 iscoupled (e.g., by laser welding) to a portion of the housing of the cellor to a terminal of the cell. According to another exemplary embodiment,the inner member 844 is coupled to the edge of an electrode of the cellelement and the outer portion 850 of the arms 842 and/or the outermember 848 are coupled to the housing or the terminal.

According to an exemplary embodiment, the geometry of the outer members848, arms 842, and inner member 844 define a plurality of apertures orslots. These apertures or slots allow the current collector 840 tosubstantially flex (e.g., move, bend, deflect, etc.) if required (e.g.,when a vent deploys from the bottom of the housing). For example, theinner member 844 is configured to flex with respect to the outer member848 (or vice-versa). It should be noted that the arms 842 arerotationally symmetric. For example, rotation of the current collector742 approximately 180 degrees about the axis 638 results in asubstantially identical orientation.

Referring now to FIGS. 24A-24D, according to an exemplary embodiment,the cell 24 includes a vent 70. The vent 70 is configured to allow gasesand/or effluent to exit the cell 24 once the pressure inside the cell 24reaches a predetermined amount (e.g., during a rise in celltemperature). When the vent 70 deploys (e.g., activates, opens,separates, etc.), the gases and/or effluent inside the cell 24 exit thecell 24 in order to lower the pressure inside the cell 24 (e.g., asrepresented by arrows 76 shown in FIG. 24B). According to an exemplaryembodiment, the vent 70 acts as a safety device for the cell 24 during ahigh pressure occurrence.

According to an exemplary embodiment, the vent 70 is located in thebottom or bottom portion of the housing 25. According to other exemplaryembodiments, the vent 70 may be located elsewhere (e.g., such as in thelid or cover of the cell). According to another exemplary embodiment,the vent 70 may be located in a cover or bottom that is a separatecomponent from the housing 25 that in turn is coupled to the housing 25(e.g., by a welding operation).

According to an exemplary embodiment, the bottom of the housing 25 mayinclude a ridge, projection, or ring of material 74 (e.g., as shown inFIGS. 24A and 24B) to prevent fracture of the vent 70 during handlingand/or assembly of the cell 24. The ring of material 74 provides for aclearance space between the vent 70 and a surface that the cell 24 isset upon. According to an exemplary embodiment, the clearance space isconfigured to prevent the vent 70 from being accidentally bumped (anddeployed) during handling and/or assembly of the cell 24.

As shown in FIG. 24A, the vent 70 includes at least one annular fracturegroove 72 (e.g., ring, trough, pressure point, fracture point, fracturering, etc.). According to an exemplary embodiment, the annular fracturegroove 72 has a V-shaped bottom and is configured to break away (i.e.,separate) from the bottom of the housing 25 when the vent 70 deploys.According to other exemplary embodiments, the bottom of the annularfracture groove 72 may have another shape (e.g., rounded shape, curvedshape, U-shape, etc.).

As stated earlier, the vent 70 is configured to deploy in the directionalong or parallel to the axis 638 once the pressure inside the cell 24reaches a predetermined amount. When the vent 70 deploys, the annularfracture groove 72 fractures and separates the vent 70 from the rest ofthe bottom of the housing 25, allowing the internal gases and/oreffluent to escape the cell (e.g., as shown in FIG. 24B). By having thevent 70 separate from the bottom of the housing 25, the vent 70 acts asa current interrupt or current disconnect device. This is because theseparation of the vent 70 from the bottom of the housing 25 along theaxis 638 disrupts the flow of current from the cell element 30 (throughthe positive current collector 640) to the housing 25. In this way, thevent 70 acts not only as an over-pressure safety device, but also as acurrent disconnect device. In order to help insulate the cell element 30and the current collector 640 from the housing 25, the insulative wrap46 may include an extension 47 provided between the current collector640 and the bottom of the housing 25.

According to an exemplary embodiment, the vent 70 (e.g., the annularfracture groove 72) is formed by tooling located external the housing25. The tooling tolerance is only affected by one side of the tool,allowing for a more consistent annular fracture groove 72, resulting ina more consistent and repeatable opening of the vent 70. The depth,shape, and size of the fracture groove 72 may be easily modified simplyby changing the tooling. Additionally, the vent 70 is easy to clean andinspect since the vent 70 (and annular fracture groove 72) is located onan external side of the housing 25.

According to one exemplary embodiment, the cell element 30 does not moveduring deployment of the vent 70 (i.e., the cell element remainsstationary). According to such exemplary embodiments, flexible currentcollectors may be utilized (e.g., such as the current collector 640shown in FIGS. 21 and 24A-C, the current collector 740 shown in FIG. 22,or the current collector 840 shown in FIG. 23). According to otherexemplary embodiments, the cell element 30 may move in order to helpdeploy the vent 70 (e.g., by “pushing” or “punching” the currentcollector through the vent). According to such exemplary embodiments,non-flexible current collectors may be utilized (e.g., such as thecurrent collector 340 shown in FIGS. 14-17, the current collector 440shown in FIG. 19, or the current collector 540 shown in FIG. 20.).

Referring now to FIG. 24D, a housing 125 for an electrochemical cell isshown according to another exemplary embodiment. The housing 125includes a vent 170 provided in a bottom portion of the housing 125.According to other exemplary embodiments, the vent 170 may be providedelsewhere (e.g., such as in the lid or cover of the cell). According toanother exemplary embodiment, the vent 170 may be located in a cover orbottom that is a separate component from the housing 125 that in turn iscoupled to the housing 125 (e.g., by a welding operation).

According to an exemplary embodiment, the bottom of the housing 125 mayinclude a ridge, projection, or ring of material 174 to prevent fractureof the vent 170 during handling and/or assembly of the cell. The ring ofmaterial 174 provides for a clearance space between the vent 170 and asurface that the cell is set upon. According to an exemplary embodiment,the clearance space is configured to prevent the vent 170 from beingaccidentally bumped (and deployed) during handling and/or assembly ofthe cell.

As shown in FIG. 24D, the vent 170 includes at least one annularfracture groove 172 (e.g., ring, trough, pressure point, fracture point,fracture ring, etc.). According to an exemplary embodiment, the annularfracture groove 172 has a V-shaped bottom and is configured to breakaway (i.e., separate) from the bottom of the housing 125 when the vent170 deploys. According to other exemplary embodiments, the bottom of theannular fracture groove 172 may have another shape (e.g., rounded shape,curved shape, U-shape, etc.).

Referring now to FIGS. 25-29, a member or element provided in the formof a current collector or collector plate 940 is shown according to anexemplary embodiment. As shown best in FIG. 29, the current collector940 is used to conductively couple an end of the electrode (e.g., thenegative electrode 38) of the cell element 30 to a terminal (e.g., thenegative terminal 28).

The current collector 940 may be formed from a stamping process, a lasercutting process, or other suitable process. According to an exemplaryembodiment, the current collector 940 may be formed from a materialhaving a thickness of between approximately 1 and 2 millimeters, but mayhave a greater or lesser thickness according other exemplaryembodiments. According to various exemplary embodiments, the currentcollector 940 may be formed from any of a wide variety of conductivematerials such as aluminum or an aluminum alloy (e.g., for a positivecurrent collector), copper or a copper alloy (e.g., for a negativecurrent collector), nickel-plated copper or an alloy thereof, etc.

Referring to FIGS. 26-27, the current collector 940 is provided in theform of a generally flat member having a main body 942. Extending outfrom one end of the main body 942 is at least one tab or extension 944(shown in FIG. 27 as at least partially folded over the main body 942).According to an exemplary embodiment, the tab 944 is at least partiallyfolded over the main body 942 multiple times (e.g., similar to the tab44 shown in FIG. 4). According to an exemplary embodiment, the main body942 includes a hole or aperture 950 (e.g., as shown in FIG. 26). Theaperture 950 may be provided as generally aligned with the center of thecell element 30.

According to an exemplary embodiment, the tab 944 is configured to becoupled to a terminal (e.g., the negative terminal) of the cell (e.g.,by laser welding). The tab 944 provides a substantially flexibleconnection between the electrode of the cell element and the terminaland allows the cell element to move relative to the terminal or housingif required.

According to an exemplary embodiment, the current collector 940 alsoincludes a plurality of members or extensions shown as arms 948 that areconfigured to project or extend out from the main body 942 of thecurrent collector 940. The arms 948, along with the main body 942 of thecurrent collector 940, extend out across one end of the cell element 30(e.g., to contact the edge of the negative electrode 38 such as shown inFIG. 25). According to another exemplary embodiment, the arms 948 andmain body 942 of the current collector 940 may extend only partiallyacross the end of the cell element 30. While two arms 948 are shown inthe exemplary embodiment of FIGS. 25-29, according to other exemplaryembodiments, the current collector 940 may have a greater or lessernumber of arms 948.

As best seen in FIG. 25, the outer edge of the arms 948 may include arounded or curved shape to complement the perimeter of the cell element30. According to other exemplary embodiments, the arms 948 (includingthe ends of the arms) may have other shapes and/or sizes. The currentcollector 940 may be coupled to the electrode 38 with a weldingoperation (e.g., a laser welding operation) along the arms 948 and mainbody 942 of the current collector 940.

According to an exemplary embodiment, radial welds are used (e.g., suchas along weld lines 946 as shown in FIG. 25) to couple the currentcollector 940 to the electrode 38. According to one exemplaryembodiment, the radial welds extend from the center of the main body 942out to the outer edges of the main body 942 and arms 948. According toother exemplary embodiments, the welds (radial or otherwise) may beformed differently. According to an exemplary embodiment, the welding ofthe current collector 940 to the electrode is done prior to the foldingof the tab 944, but may occur at a different time according to otherexemplary embodiments.

The use of radial welds (i.e., welds that are radial with respect to theedge of the electrode of the cell element 30) allows for more efficientcurrent flow from the electrode of the cell element 30 to the currentcollector 940 in that all of the portions of the edge of the woundelectrode are coupled (e.g., welded) to the current collector 940 (viathe arms 948 and the main body 942). Additionally, radial welds on awound cell element (such as shown in FIG. 25) allow the weld to occursubstantially perpendicular to the edge of the electrode, providing forbetter weld control and repeatability of the weld from one cell to thenext.

While the current collectors of FIGS. 8-13B and 25-29 are generallyshown as being coupled to a negative electrode, according to otherexemplary embodiments they may be coupled to a positive electrode.Likewise, while the current collectors of FIGS. 14-24C are generallyshown as coupled to a positive electrode, according to other exemplaryembodiments they may be coupled to a negative electrode. Furthermore,while the current collectors shown in FIGS. 8-29 are configured for usewith wound cell elements, according to another exemplary embodiment, thecurrent collectors may also be used with a series of flat plates (e.g.,prismatic cells) or other cell configurations.

According to various exemplary embodiments, the current collectors shownin FIGS. 8-29 may be formed from a relatively thin sheet of conductivematerial (e.g., by a stamping operation, a laser cutting operation,etc.) or may be formed by an extrusion process. According to variousexemplary embodiments, the current collectors may be substantially rigidor may include a flexible or pliable portion (such as, e.g., the tabsshown in FIGS. 8-13 and 25-29 or the arms shown in FIGS. 21-23).

Referring now to FIG. 30, an assembly process used to make a battery orelectrochemical cell is shown according to an exemplary embodiment. In afirst step 1010, the separators and electrodes are wound around themandrel to form the cell element in a jelly roll configuration. In asecond step 1020A/1020B, the positive and negative current collectorsare electrically or conductively coupled (e.g., by a welding operationsuch as laser welding) to the positive and negative electrode ends ofthe jelly roll, respectively. According to various exemplaryembodiments, the step 1020A may occur before, after, or concurrent withthe step 1020B.

In a third step 1030, the jelly roll is inserted into the cell housing.In a fourth step 1040, the positive current collector is electrically orconductively coupled (e.g., by a welding operation) to the base of thecell housing. In a fifth step 1050, the negative current collector iselectrically or conductively coupled (e.g., by a welding operation) tothe insulated terminal of the cap of the cell. In a sixth step 1060, thecap of the cell is coupled to the housing of the cell (e.g., by awelding operation).

According to an exemplary embodiment, a current collector or plate foran electrochemical cell includes a member having a first surface and asecond surface opposite the first surface. The second surface comprisesat least one projection. The member is configured to be coupled to anelectrode of the cell, the electrode having a wound configuration. Theat least one projection is configured to engage an offset edge of theelectrode so that the member can be welded to the cell.

Another embodiment of the invention relates to a current collector orplate for an electrochemical cell including a member. The memberincludes a main body and at least two legs extending out from a firstend of the body. The legs are configured to engage an offset edge of awound electrode of the cell so that the member can be welded to thecell.

One embodiment of the invention relates to a substantially flexiblecurrent collector for an electrochemical cell. The current collectorincludes a plurality of members coupled to a cell element and an innerring coupled to a bottom of a housing.

Another embodiment of the invention relates to a current collector foran electrochemical cell. The current collector includes a main body andat least one arm extending out from a first end of the main body. Themain body and the at least one arm are configured to be conductivelycoupled to a cell element. The current collector also includes a memberextending out from the main body, the member being singularly foldedpartially over the main body. An end of the member is configured to beconductively coupled a terminal of the cell.

As utilized herein, the terms “approximately,” “about,” “substantially,”and similar terms are intended to have a broad meaning in harmony withthe common and accepted usage by those of ordinary skill in the art towhich the subject matter of this disclosure pertains. It should beunderstood by those of skill in the art who review this disclosure thatthese terms are intended to allow a description of certain featuresdescribed and claimed without restricting the scope of these features tothe precise numerical ranges provided. Accordingly, these terms shouldbe interpreted as indicating that insubstantial or inconsequentialmodifications or alterations of the subject matter described and claimedare considered to be within the scope of the invention as recited in theappended claims.

It should be noted that the term “exemplary” as used herein to describevarious embodiments is intended to indicate that such embodiments arepossible examples, representations, and/or illustrations of possibleembodiments (and such term is not intended to connote that suchembodiments are necessarily extraordinary or superlative examples).

The terms “coupled,” “connected,” and the like as used herein mean thejoining of two members directly or indirectly to one another. Suchjoining may be stationary (e.g., permanent) or moveable (e.g., removableor releasable). Such joining may be achieved with the two members or thetwo members and any additional intermediate members being integrallyformed as a single unitary body with one another or with the two membersor the two members and any additional intermediate members beingattached to one another.

References herein to the positions of elements (e.g., “top,” “bottom,”“above,” “below,” etc.) are merely used to describe the orientation ofvarious elements in the FIGURES. It should be noted that the orientationof various elements may differ according to other exemplary embodiments,and that such variations are intended to be encompassed by the presentdisclosure.

It is important to note that the construction and arrangement of thecurrent collectors for an electrochemical cell as shown in the variousexemplary embodiments is illustrative only. Although only a fewembodiments have been described in detail in this disclosure, thoseskilled in the art who review this disclosure will readily appreciatethat many modifications are possible (e.g., variations in sizes,dimensions, structures, shapes and proportions of the various elements,values of parameters, mounting arrangements, use of materials, colors,orientations, etc.) without materially departing from the novelteachings and advantages of the subject matter described herein. Forexample, elements shown as integrally formed may be constructed ofmultiple parts or elements, the position of elements may be reversed orotherwise varied, and the nature or number of discrete elements orpositions may be altered or varied. The order or sequence of any processor method steps may be varied or re-sequenced according to alternativeembodiments. Other substitutions, modifications, changes and omissionsmay also be made in the design, operating conditions and arrangement ofthe various exemplary embodiments without departing from the scope ofthe present invention.

What is claimed is:
 1. A battery comprising: a housing; a cell elementdisposed within the housing; a vent member coupled to the housing; and acurrent collector, comprising: an inner member coupled to the ventmember; an outer member coupled to the cell element; and a plurality offlexible arms extending between the inner member and the outer memberand configured to allow the inner member to move in a direction relativeto the outer member, wherein the direction comprises both an axialcomponent along an axis of the current collector and a circumferentialcomponent about the axis.
 2. The battery of claim 1, wherein a portionof the plurality of flexible arms is welded to the cell element,defining a first weld line, the inner member is welded to the ventmember, defining a second weld line, and wherein the first and secondweld lines skew when the inner member moves in the direction.
 3. Thebattery of claim 1, wherein at least one arm of the plurality of armsincreases in width from the inner member toward the outer member.
 4. Thebattery of claim 1, wherein the plurality of flexible arms arerotationally symmetric.
 5. The battery of claim 4, wherein the pluralityof flexible arms comprise a degree of rotational symmetry in a range of90 degrees to 180 degrees.
 6. The battery of claim 1, wherein each armof the plurality of arms is substantially arcuate from the inner membertoward the outer member.
 7. The battery of claim 6, wherein each arm hasa spiral shape about the inner member.
 8. The battery of claim 1,wherein the vent member is coupled to a bottom portion of the housing.9. The battery of claim 1, wherein the vent member is coupled to a lidor cover portion of a housing.
 10. The battery of claim 1, wherein aperimeter of the outer member is substantially the same as a perimeterof a top or bottom face of the housing.
 11. The battery of claim 1,wherein the vent member includes at least one fracture groove configuredto separate from the vent member from the housing when the vent memberdeploys to enable the release of gases and/or effluent from the batterycell.
 12. The battery of claim 11, wherein the at least one fracturegroove is an annular fracture groove having a V-shaped bottom.
 13. Acurrent collector for a battery cell, comprising: a first memberconfigured to be coupled to a cell element of the battery cell; and asecond member that is coupled to the first member, wherein the secondmember is configured to be coupled to a vent member of the battery cell,and wherein the second member is configured to move away from the firstmember and to twist relative to the first member when the vent member ofthe battery cell deploys.
 14. The current collector of claim 13, whereinthe first member is an inner member of the current collector, andwherein the second member is an outer member of the current collector.15. The current collector of claim 14, wherein the first member is anouter member of the current collector, and wherein the second member isan inner member of the current collector.
 16. The current collector ofclaim 14, comprising a plurality of arms that is coupled to both thefirst member and the second member, wherein the plurality of arms definea plurality of slots between the first member, the second member, andthe plurality of arms.
 17. The current collector of claim 16, whereinthe plurality of slots is configured to expand when the vent member ofthe battery cell deploys to allow the passage of gases and/or effluentout of the battery cell.
 18. The current collector of claim 14, whereinthe current collector is a positive current collector made from copperor copper alloy.
 19. The current collector of claim 14, wherein thecurrent collector is a negative current collector made from aluminum oraluminum alloy.
 20. The current collector of claim 14, wherein thecurrent collector has a thickness of between approximately 1 millimeter(mm) and 2 mm.
 21. A method, comprising: deploying a vent member of abattery cell during operation, wherein the vent member is coupled to aninner member of a current collector; and displacing the inner member ofthe current collector relative to an outer member of the currentcollector as the vent member deploys, wherein displacing comprises axialdisplacement along an axis and a rotational displacement about the axis.22. The method of claim 21, comprising expanding one or more aperturesdisposed between the inner member and the outer member of the currentcollector as the vent member deploys to faciliate a release of gasesand/or effluent from of the battery cell.
 23. The method of claim 21,wherein deploying the vent member comprises detaching the vent memberfrom a housing of the battery cell along a fracture groove to facilitatea release of gases and/or effluent from the battery cell.
 24. The methodof claim 23, wherein detaching the vent member from a housing of thebattery cell along a fracture groove comprises separating the ventmember from the housing once a pressure inside the battery cell reachesa predetermined amount.
 25. The method of claim 21, wherein deployingthe vent member comprises bending a plurality of arms of the currentcollector extending between the inner member and the outer member toenable the axial and rotational displacement of the inner member as thevent member deploys.